Field of the Invention
The invention relates to an image sensor having a multiplicity of pixel sensor regions and having an optical configuration, which images an image to be recorded by the image sensor onto the sensor regions.
Image sensors are known in which pixel sensor elements in the form of so-called charge coupled devices (CCDs) or CMOS sensor elements constructed using CMOS technology are used as pixel sensor regions. The sensor elements are usually joined together in such a way that a contiguous sensor area of the image sensor is formed overall. An image that is imaged onto the sensor area by the optical configuration is converted into electrical signals by the sensor elements, each sensor element corresponding to a pixel of the recorded image. In this case, the resolution of the image sensors is dependent upon the resolution of the optical configuration used and the dimensions of the sensor elements.
Production-dictated tolerances of the optical and electrical properties of the individual sensor elements can occur in image sensors. This is the case, for example, to a great extent with CMOS sensor elements (CMOS pixel sensor). As a result of the production-dictated tolerances, varying electrical signals, which become apparent as so-called fixed pattern noise (FPN) and as signal noise, are produced for different sensor elements even in the event of irradiation with the same quantity of light. In order to compensate for these undesired tolerances, special compensation circuits are necessary.
Published, Non-Prosecuted German,Patent Application DE 195 24 577 A1 describes an image sensor. The measured values of a plurality of sensor elements are averaged by addition of charges generated during the measurement by the individual sensor elements. A/D conversion of the summed charges is then carried out.